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Groundwater is one of the alternatives to surface water that can be used for drinking water; however, it normally exists with high iron and manganese content. In this study, a column study was conducted to observe the elimination of iron (Fe) and manganese (Mn) in the groundwater under different retention times by using zeolite immobilized with iron‐oxidizing bacteria (IOB). Rossellomorea sp., representing an IOB, was found from the isolation process and was further cultured in the laboratory for immobilization into the natural zeolite as replacement materials for the sand filter. When the zeolite assisted with the Rossellomorea sp. was used, the elimination of Fe and Mn were 99.34% and 88.92%, respectively, compared to the removal of Fe and Mn, which were 93.62% and 93.73%, respectively, for media without immobilization. The presence of Rossellomorea sp. enhances the Fe oxidation, resulting in high removal of Fe. The Thomas and Yoon–Nelson models were performed in both raw zeolite and zeolite with IOB. The total coliform (most probable number [MPN]) increased from 70.8 to 307.6 MPN/100 mL because of the Rossellomorea sp. present that promotes the growth of coliform bacteria. In conclusion, the immobilization of zeolite with IOB is a potential technique to extract the Fe and Mn in the groundwater. Practitioner Points: Zeolite incorporated with Rossellomorea sp. has higher removal performance of Fe, whereas the removal of Mn reduced compared to the raw zeolite.The presence of Rossellomorea sp. enhances the oxidation of ferrous iron and improves the removal of Fe in the groundwater because the ferric iron is the priority ion to be exchanged.The removal of UV254 increase when Rossellomorea sp. present in the zeolite because the Rossellomorea sp. consume the natural organic matter as carbon source. [ABSTRACT FROM AUTHOR]

The ability of a commercial‐scale Cyclobio fluidized sand filter was evaluated for ammonia and nitrite removal by dosing with ammonia chloride, NH4Cl, as part of the water treatment unit for the U.S. Department of Agriculture Agricultural Research Service Warmwater Aquaculture Research Unit's (WARU) catfish hatchery in Stoneville, Mississippi, USA. Treatment system water was recirculated through the Cyclobio filter for several months without any feed inputs; thus, our objective was to investigate how quickly a full‐scale Cyclobio fluidized sand filter could be reactivated with NH4Cl substrate dosing in preparation for the upcoming spawning season. A second objective of the study was to examine the decline of the filter's nitrification ability when the supplementary NH4Cl substrate dosings were removed or limited. The effects of daily and weekly substrate additions were evaluated over a 14‐week winter period, with the system water temperature ranging between 20° and 23°C. Total ammonia nitrogen (TAN) concentration decreased within hours of initial dosing. After approximately a 2‐h lag period, the nitrite–nitrogen concentration peaked and then decreased. The rate of TAN nitrification followed a simple first‐order reaction kinetics and increased over time during the 4 weeks of daily NH4Cl substrate dosing. The return to a weekly substrate dosage resulted in a decrease in the kinetic reaction rate, but adequate to maintain the filter during periods of system inactivity. The once‐daily substrate dosage was consumed within hours of the initial dosing and was sufficient for current system loading. [ABSTRACT FROM AUTHOR]

Adopting a greywater treatment system that provides economical, effective, and sustainable treated greywater over a longer span helps to address water scarcity. The present study focuses on treating greywater generated from hostels using a floating plant treatment system (FPTS) planted with water hyacinth. The additional units, a sand filter and an activated charcoal filter, were attached in series to FPTS to improve the treated greywater quality. The treatment system was operated for 90 days with daily monitoring of influent and effluent parameters. The treatment performance was evaluated based on the removal efficiency for total suspended solids (TSS), turbidity, chemical oxygen demand (COD), ammonia, sulphate, phosphate, and faecal coliform (FC) of 74.81% ± 5.74%, 99.76% ± 0.05%, 95.70% ± 4.10%, 99.16% ± 2.08%, 48.22% ± 1.80%, and 100%, 97.27% ± 1.48%, respectively. The study showed that the system effectively treats greywater, making it suitable for non‐potable purposes on educational institution's campuses. [ABSTRACT FROM AUTHOR]

Composite materials are susceptible to environmental threats correlated to moisture absorption, which affects the bonding performance of the joints. Therefore, drying should be taken into account during actual manufacturing operations. In this work, the influence of moisture absorption‐drying of composite materials on the bonding performance of the joints is investigated to provide a theoretical direction for the co‐bonding process. Firstly, the surfaces of composite materials are treated with three methods: sanding, dry peel ply, and wet peel ply. Secondly, the composite materials are subjected to moisture absorption‐drying treatment at 26 °C/65% relative humidity (RH) and 70 °C/85% RH. Finally, the above materials are bonded to evaluate the bonding performance. These results show that the bonding performance of the joints treated with two peel plies decreases significantly after moisture absorption. After moisture absorption‐drying at 26 °C/65% RH, the bonding performance of the joints treated with dry peel ply cannot fully recover, while wet peel ply can be fully recoverable. However, the bonding performance of all joints cannot fully recover after absorbing moisture‐drying at 70 °C/85% RH, whose recovery has relations with surface treatment. [ABSTRACT FROM AUTHOR]

Oil pollution results from daily activities and a variety of industries have caused not only severe environmental problems but also wastage of valuable petrochemical resources. Separation based on superwettable materials holds promise; however, practical applications of a single type of superwettable materials were often limited due to their ability in treatment of complicated oil‐water systems. Herein, a Gemini‐type separator was created through the cooperation of two kinds of superwettable sand particles with opposite wettability, i. e. one is superhydrophobic whereas the other is superhydrophilic. Cooperatively by the two types of superwettable sand, consecutive separation and purification of both water and oil phases from complicated oil‐water systems (e. g. water mixed with a lighter or denser oil, water emulsified in oil, oil emulsified in water, and/or a combination of them in one batch) could be achieved with high flux and superior efficiency just in one single operation unit. [ABSTRACT FROM AUTHOR]

Laundry processes are huge water consumers and contribute to wastewaters in high volume. In the current report, treatment of greywater (GW) was studied from commercial laundry in BITS Pilani, KK Birla Goa Campus, India, which produces around 2–2.5 m3/day of GW. Source laundry GW showed physicochemical parameters like chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammoniacal N (NH4–N), nitrate (NO3–N), nitrite (NO2–N), orthophosphate (PO4–P) and pH in the range of 600–650 mg/L, 350–370 mg/L, 9–12 mg/L, 15–21 mg/L, 14–22 mg/L, 28–35 mg/L and 7.48–8.10, respectively. The treatment system included French‐type two‐stage vertical flow constructed wetland (VFCW) preceded by anaerobic filter tank filled with 3D plastic support. Wetland beds were made up of sand and gravel as filter media, and Canna indica was used as macrophyte. Pretreatment by anaerobic filter resulted in the increase in residence time of GW and reduction of pollutant load to wetland beds, thus preventing clogging of Stage 1 wetland. Sampling and water quality data analysis was performed weekly for 26 weeks. Outlet pollutant levels showed 96.35% removal of organic matter, 79.93% removal of nitrogen and 95.04% removal of orthophosphates. The pH of outlet water was 7.35, which is well below discharge permissible limits. Treated water quality was below Central Pollution Control Board (CPCB), India, permissible limits for discharge, and the cost of treating GW by the system is 1.11 USD/m3 which is very feasible in country like India. Treated water is suitable for nonpotable options like gardening of central lawns in BITS Pilani Goa, floor cleaning of laundry and construction purpose. [ABSTRACT FROM AUTHOR]

This study focused on evaluating the feasibility of expanded clay and sand as media types for mainstream partial denitrification‐anammox (PdNA) in deep‐bed single‐media polishing filters under nitrogen and solids loading rates as well as backwash conditions similar to conventional denitrification filters. The surface roughness and iron content of the expanded clay were hypothesized to allow for enhanced anammox retention, nitrogen removal rates, and runtimes. However, under the tested loading rates and backwash conditions, no clear benefit of expanded clay was observed compared with conventional sand. This study showed the feasibility of PdNA in filters with both sand and expanded clay with PdN efficiencies of 76% and 77%, PdNA rates of 840 and 843 g N/m3/d and TIN removal rates of 960 and 964 g N/m3/d, respectively. Glycerol demands were 1.5–1.6 g COD added per g TIN removed, thus indicating potential carbon savings up to 75% compared with conventional denitrification. Overall, this study showed for the first time PdNA filters performing at nitrogen removal rates double that of previous PdNA studies under realistic conditions while providing insights into the media choice and backwashing conditions. Future research on expanded clay backwash conditions is needed to provide its full potential in PdNA filters. Practitioner Points: Hydraulic and TSS loading rates similar to conventional denitrification can be applied in PdNA filters.Conventional sand can be used when retrofitting conventional denitrification filters into PdNA filters.Carbon savings up to 75% can be achieved with glycerol when retrofitting conventional filters into PdNA filters [ABSTRACT FROM AUTHOR]

Fluoride concentration in groundwater above than the prescribed value by WHO (>1.5 mg/L) has led to severe health issues. One of the fluoride removal techniques that are low cost and highly efficient is the coagulation technique. Aluminum salts are used as coagulants along with lime to maintain desired pH. The main drawback of this technique is the large concentration of aluminum in treated water. Therefore, the present study aims to lower down the aluminum concentration in the defluoridated water within the acceptable limits by applying sand filter and ultrafiltration membrane subsequently. Aluminum removal efficiency of ultrafiltration was almost 90% and 70% for sand filtration. In terms of energy consumption, ultrafiltration consumed 60 kWh/m3 and sand filtration consumed 6.2 kWh/m3. Cost analysis was also done and it was observed that sand filter was more cost effective than ultrafiltration. Also, ultrafiltration consumed 10 times higher energy than sand filter for treating 1 m3 of water. [ABSTRACT FROM AUTHOR]

This study evaluated clogging effects on head loss and water quality in sand prefiltration columns, followed by innovative double‐layered slow‐filter filtration technology using anthracite coal and sand. The study was divided into two phases. Phase 1 (filtration rate 11 m3/m2·d) had a layout of a pre‐filter (PF) system followed by a slow filter (SF). In Phase 2 (filtration rates of 5.5 and 11 m3/m2·d), two PF systems (PF1 and PF2) followed by SFs (SF1 and SF2) were monitored, be differed only by filtration rate. Phase 1 presents a mean turbidity removal of 45.6% in PF and 23.9% in SF. PF presented a lower head loss in the superficial layers of the filter media, whereas SF presented a more important contribution in the deeper layers of the bed. In Phase 2, the mean results obtained for turbidity removal in PF1 and SF1 were 84.7% and 22.4%, in that order. PF2 and SF2 promoted mean reductions of 84.5% and 22.0%, respectively. Greater clogging is observed in the PF's surface layers, whereas the SFs dissipate greater clogging with depth. Filtration rates and water quality were similar in filter media of different compositions. Practitioner Points: Double‐layer filters show better use of the porous media in depth.Different materials produce different forms of clogging.Higher filtration rates increase the number of pre‐filter and slow filter runs. [ABSTRACT FROM AUTHOR]

Natural porous media possess spatial heterogeneous (fractional) wettability, which controls the multiphase flow behavior, that is, displacement and trapping. We used mixed hydrophilic (contact angle θ = 0°) and hydrophobic (θ = 100°) 1 mm sands and 1 mm glass beads as model systems for fractional wet porous media. Both porous media have the same morphological characteristics (Minkowski functions). A comparative μ‐CT study of such fractional wet systems is lacking in the literature. A previous study (Geistlinger & Zulfiqar, 2020, https://doi.org/10.1029/2019wr026826) showed a percolation transition of the invading fluid from compact to fractal displacement when the wettability changed from imbibition to drainage. This correlates to a transition from no to maximal trapping. For the first time, we observed in fractional wet glass bead packs, a second structural percolation transition with a percolation threshold of approximately 50% hydrophobic glass beads. Below this threshold, the percolating cluster consisted of hydrophilic glass beads, which resulted in compact displacement without any trapping. Above the threshold, the percolating cluster consisted of hydrophobic glass beads, which resulted in fractal displacement with maximal trapping. Trapping occurred only in hydrophobic environments/configurations, that is, when the trapped clusters were surrounded by hydrophobic glass beads. Fractional wet glass beads and sands show an opposite trapping behavior, that is, the trapping efficiency increases for glass beads, whereas it decreases for sands with increasing percentage of hydrophobic grains. Interestingly, the trapping efficiency approaches the same limit value for pure hydrophobic sands and glass beads. This demonstrates that bypass trapping is the dominant trapping mechanism, because it depends strongly on the pore connectivity. Key Points: Fractional wet glass beads and sands with same morphological properties (pore space connectivity) show an opposite trapping behaviorPure hydrophobic sands and glass beads show equal trapping efficiency caused by bypass trapping (equal pore space connectivity)Structural (site) percolation transition with a percolation threshold of approximately 50% hydrophobic glass beads [ABSTRACT FROM AUTHOR]

The combined effects of gravitational forces and wettability on displacement and trapping have not previously been investigated experimentally in realistic 2D porous media. Here we report the first use of representative 2D micromodels that accurately reproduce characteristic geometric, morphological, and topological properties of 3D sand packs. We use these representative micromodels to compare the wettability dependence of displacement front morphology and trapping processes using selected fluid pairs at capillary numbers between 10−6 and 10−5. The contact angles studied ranged from 30° (normal imbibition) to 150° (strong drainage). The impact of gravity was dramatic: In the horizontal flow case, only one finger developed, that is longitudinal displacement was always favored, whereas gravity created a more compact displacement front with broad lateral extension, and this lateral movement created loops, leading to by‐pass trapping. As a result, the trapping efficiency rose from 7% to 29%. We observed universal scaling of the cluster size distribution demonstrating that our micromodels are statistically representative. The universal 2D‐scaling exponent of 2.05 was obtained with an acceptable error smaller than 5%. Our experimental results obtained by fluorescence microscopy showed (a) precursor corner flow for weak imbibition at θ = 51°, that is above the critical contact angle of αc = 45° (Zhao et al., 2016, https://doi.org/10.1073/pnas.1603387113), and (b) a new wetting transition from corner flow to full duct flow under neutral wettability conditions, that is at θc ≈ 90°; and (c) above this second critical contact angle, that is under strong drainage conditions, we again observed corner flow (specifically, core‐annular flow). Key Points: Micromodel‐study of the interplay between wettability, surface roughness and trapping efficiency using representative Si‐micromodelsComparison of the horizontal and vertical displacement process to investigate the combined effect of wettability and gravityStudy of precursor corner flow from normal imbibition (30°) to strong drainage (150°) [ABSTRACT FROM AUTHOR]

Most organic ultraviolet filters are very lipophilic and some of them are difficult to quantify in the environment. This article describes an optimization method for the quantification of these compounds in sand samples with diverse compositions. The standard additions method was used. The search for a unique high‐performance liquid chromatography method to analyze all these filters along with the search for optimal detection conditions are presented in detail. The best extraction solvent was methanol, and the best conditions for analysis and detection involved the use of a high‐performance liquid chromatography system equipped with a biphenyl column (2.6 μm, 150 × 4.6 mm), and an Orbitrap MS detector. We also demonstrated that sample freeze‐drying can induce significant loss of some of the ultraviolet filters. [ABSTRACT FROM AUTHOR]

The purpose of this study is to optimize the operating conditions in batch mode using Box‐Behnken Design (BBD), for the coagulation‐flocculation line sizing prior the sand filter in the pilot scale. Three coagulants were employed to achieve a high turbidity removal with a low concentration of residual metals. The results showed that the best turbidity removal was obtained with FeCl3. Using BBD (15 experiments), the optimal parameters were: coagulant dose = 5.5 mg FeCl3/L, slow stirring time = 33 min and slow stirring velocity = 45 rpm, in these conditions, the turbidity removal reached 94.89% and the residual iron concentration was 0.449 mg/L. Regarding the model fit, the obtained R2 values were 99.67% for turbidity removal and 99.47% for residual iron concentration. The optimum conditions obtained from this study could be scaled up and applied to desalination plants. BBD approach is of great interest because it allows the prediction of the response value without performing experiments. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) are engineered systems for treating wastewater by sequestering nutrients and contaminants. Our aim was to assess the main phosphorus (P) binding states in operating CWs to assess P saturation and indications on P recycling potential of filter materials, which might be necessary under future peak P scenarios. The investigated vertical flow CWs (operation time up to 16 years) are based on either fluviatile (Fluv) sand or zeolite‐ (Ze‐LS) and clinopyroxene (Cl‐LS)‐dominated lava sand. Organic and inorganic P accumulated in all CWs independent of filter materials and showed a considerable increase with operation time. Concentrations of P decreased sharply with depth in the Fluv‐CWs compared to only a slight decrease in the lava sand CWs, with P concentrations of deeper horizons approximating the relatively P enriched original lava sand substrates. Orthophosphate was the dominant pool in all CWs, while the sum of organic fractions ranged between 11% and 33%. Sequential extraction indicated that P was mainly associated with Fe and Al (hydr)oxides for Fluv‐CWs and Ze‐LS‐CWs, while Ca and Mg bound mineral phosphates dominated in Cl‐LS‐CWs. Oxalate extractions pointed to a clear dominance of P fractions associated with poorly crystalline Fe‐ and Al‐(oxy)hydroxides. Solution 31P NMR analyses revealed that inositol hexakisphosphates were a major pool of organic P in surface layers of CWs, which increased with operation time. With a maximum of 0.5% P content, filter sands do not appear to be a suitable fertilizer for direct application to agricultural fields. The dominance of inorganic, poorly crystalline P species point to potentially high desorption capacity which might be investigated further, to assess recycling potential of P or usage of filter materials as soil amendments with relatively high plant available P. The latter might become feasible and economically attractive under future P scarcity. Simultaneously, P saturation indexes (DPS) did not indicate an imminent P saturation of filters, since P accumulation was not restricted by binding to Al and Fe minerals. [ABSTRACT FROM AUTHOR]

The photochemical degradation of chlorantraniliprole (3‐bromo‐N‐[4‐chloro‐2‐methyl‐6‐(methylcarbamoyl)phenyl]‐1‐(3‐chloro‐2‐pyridine‐2‐yl)‐1H‐pyrazole‐5‐carboxamide; CAP) was characterized under simulated solar light with 2‐nitrobenzaldehyde (2NB) actinometry. Overall, aqueous CAP degraded quickly via direct photodegradation with no significant difference observed between high‐purity water and filtered rice field water. The 24‐h average half‐life normalized to summer sunlight using 2NB was 34.5 ± 4.0 h (jCAP,env = 0.020 ± 0.0023 h−1, n = 3), and the calculated apparent quantum yield in simulated sunlight was 0.0099 ± 0.00060. These new values were used—alongside previously characterized data for air/and soil/water partitioning, degradation in soil, and hydrolysis—in the Pesticides in Flooded Applications Model to simulate CAP dissipation in a model California (USA) rice field. The model estimates an environmental half‐life of 26 d in the aqueous phase, but the bulk of applied CAP remains in the benthic zone and degrades, with estimated half‐lives of 29 and 92 d in flooded and drained fields, respectively. Environ Toxicol Chem 2020;39:1929–1935. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) reduction using stannous chloride (SnCl2) has emerged as a possible alternative to chromium treatment technologies such as strong base anion exchange. In an effort to target not only Cr(VI) reduction but, ultimately, total chromium (Cr(T)) removal, SnCl2 addition followed by rapid sand filtration was tested at the pilot scale on a groundwater with a naturally occurring Cr(VI) concentration of 0.090 mg/L. A SnCl2 dose of 1.5 mg/L, followed by filtration, was able to consistently remove Cr(T) to less than 0.010 mg/L following an initial ripening period, with limited head loss for 10 sequential 17- to 25-hr filter runs. Total tin and turbidity removal were similar, decreasing to below 0.050 mg/L and raw water levels, respectively. Analysis of filter sand following backwashes and three different material pipe segments that were exposed to unfiltered water dosed with SnCl2 indicated the accumulation of Cr and Sn on surfaces, which remains a concern. [ABSTRACT FROM AUTHOR]

Trap‐building antlion larvae detect their prey according to the substrate vibrations produced during movement of the prey on the sand surface. Although most studies are devoted to surface vibrational waves, in the present study, we determine the role of vibrations travelling through deeper sand layers. A behavioural experiment confirms that vibrational stimuli from prey insects on the surface of the sand stimulate the antlions buried in deeper sand layers to move towards the surface. Sand depth and particle size both have a strong effect on signal transmission. The damping coefficient (α10) varies from 0.49 dB to 3.30 dB cm−1 and depends on frequency (in the range from 100 to 300 Hz), particle size (from finest to coarse sand) and distance from the source of the vibrations. The deeper the sand, the narrower the frequency range of the signal becomes. Sand is a filter for higher frequencies. The smaller the sand particles, the more intense the filtering becomes. Fine sand with a mean sand particle size of 360 μm is a more efficient filter than coarse sand; consequently, high frequencies (> 2.5 kHz) are eliminated at a depth of 3 cm. Mean frequency depends on both depth and particle size. However, low frequency signals still propagate at a certain distance, which is biologically important in prey detection. Although the most efficient signal propagation appears to occur in coarse sand, it contains overly large particles that are inconvenient for relatively small antlion larvae. Predators seek a compromise between fine and coarse sand choosing medium sand. [ABSTRACT FROM AUTHOR]

The article discusses news and information on biological filtration, or biofiltration, in drinking water treatment. Topics mentioned include advancement of biofiltration science and engineering for surface water treatment facilities, the establishment of the Biological Drinking Water Treatment Committee in 2008 by the American Water Works Association, and development of a Biofiltration Focus Area by the Water Research Foundation to advance biofiltration research.

Both river bank filtration and dead-end sand filtration are becoming increasingly applied in rural areas to improve the quality of fecally contaminated water. To evaluate the capacity of both treatments to remove E. coli, fecal streptococci, and somatic and K13-phages, this study investigates their concentrations in diluted wastewater after short-distance tangential sand filtration and dead-end sand filtration. Bacteria were almost undetectable in both systems after 60 cm depth, and at a pore-water velocity of 1 m/d. Both phages underwent removal of 2.5 logs by tangential filtration, whereas dead-end filtration removed 5.1 logs and 3.9 logs of K13-phages and somatic phages, respectively. After discounting removal by the schmutzdecke, observed only in the dead-end filtration, both systems removed phages similarly. It is concluded that short-distance river bank filtration, alone, does not meet WHO requirements for drinking water. However, the concomitant reduction of suspended solids renders the filtered water amenable to further treatment steps. [ABSTRACT FROM AUTHOR]

Stormwater ponds are a common way to handle urban runoff. Different pond designs have been tested for decades to retain as much water as possible. Lately also, retention of nutrients and organic matter has become increasingly important, to reduce the eutrophication of downstream aquatic systems and thereby, e.g. fulfil the European Water Framework Directive. We have examined the load of particulate and dissolved fractions of organic matter, phosphorus, nitrogen and iron in 66 Danish ponds to determine the importance of catchment type (66 ponds) and the retention efficiency of the ponds (39 ponds) dependent on their type, age, size and design. The results showed that discharge from nutrient enriched and industrial areas is the most polluted while urban and developing areas are the least polluted. Wet ponds combined with vegetated sand filters have higher retentions of the particulate fractions (40-80%) compared with traditional wet ponds (10-20%). Generally, optimized retention requires a ratio between pond volume and impermeable catchment area of >250 m3 red.ha (reduced or impermeable hectare). Young ponds have higher retention than older ones, especially regarding the particulate fractions of organic matter, phosphorus and nitrogen. Here, 40-50% is retained in ponds <5 years, 0-30% in 5-10-year-old ponds and almost nothing in ponds >10 years. For the dissolved fractions, the trend is the same, but with lower retentions. Therefore, management and maintenance should be considered for all ponds, to avoid problems of internal loading, filling and resuspension. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Volatilization, conversion to organic acids, and conversion of acids to methane and CO SB 2 sb b. Hydrolysis, conversion to organic acids, and conversion of acids to methane and CO SB 2 sb c. Bacterial conversion of volatile organics into organic acids (e.g., acetic acid) and propionic acid, and then methane formers convert the acids into methane and CO SB 2 sb d. Enzyme conversion of volatile organics directly to methane and CO SB 2 sb B 3. After all packing rings are installed firmly, back off on the gland nuts about before the pump is started. b a. four turns b. three turns c. two turns d. one full turn B 4. A split ring that enables one to tighten the packing on the pump to prevent leaks around the shaft. b B Source: b Morgan KC, Russell DL. [Extracted from the article]

A coastal municipal water utility replaced its obsolete pressure sand filtration water treatment plant with a new state‐of‐the‐art submerged membrane plant and expected a clear path ahead for safe water. But operators soon had to reduce disinfection by‐product formation, remove manganese fouling, decrease total organic carbon, and more. [ABSTRACT FROM AUTHOR]

SUMMARY This paper presents a new interpretation method for pulse tests, a field permeability test that allows for rapid measurements of hydraulic conductivity k in aquitards. This new method applies to soft clay deposits. To initiate a pulse test, a known volume of water is injected into the sand filter of a monitoring well isolated by a packer. The resulting pressure increase yields an outward movement of the sand filter cavity wall. After presenting the usual interpretation methods and their limits, this paper proposes a new interpretation method based on a coupled analysis of the pressure and displacement fields in the soil using the Biot-Darcy formulation. A series of analytical and numerical non-dimensional velocity graphs, normalized plots of the mean hydraulic head difference versus its rate of change, are given. For a linear elastic material, these type curves show relatively small variations with the sand filter aspect ratio and the Poisson ratio of the tested clay. The type curves are also found to be independent of the clay compressibility ( mv) and k, an important result. A series of pulse tests conducted in a soft marine clay deposit near Montreal, Canada, are interpreted with the proposed method. The hydraulic conductivity values calculated from these tests are closely correlated with independent estimates obtained using long-duration variable-head tests. Compared with previous interpretation methods, the proposed method allows soil volume changes to be reconciled with cavity expansion phenomena and the range of type curves available for the interpretation of test data to be constrained. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the midst of one of the most severe droughts in centuries, resourceful operators at a North San Diego water reclamation plant manage increasingly precious effluent for community use. [ABSTRACT FROM AUTHOR]

Biosand filters (BSFs) are point-of-use water treatment systems that can provide safe and affordable potable water to households in developing countries. However, little information is available on the dynamic performance of BSFs or for selecting local materials to use as filter media. In this study, water quality dynamics, biofilm characteristics, and hydraulic performance were investigated in two full-scale BSFs. During four months of operation with sewage-contaminated surface water, average log10 removals of 1.7, 1.2, and 0.6 were observed for Escherichia coli, total coliforms, and total heterotrophs, respectively. Average removal efficiencies for turbidity, ultraviolet absorbance at 254 nm, and total organic carbon were 86, 36, and 27%, respectively. Dynamic analysis showed that significant removal of indicator organisms and total organic carbon occurred during the pause period between charging the BSFs. Biofilm characterization revealed that more particle-associated biomass exists within the BSF column compared with the schmutzdecke layer. [ABSTRACT FROM AUTHOR]

A pilot plant with successive preozonation, coagulation-sedimentation, sand filtration, postozonation, and biological activated carbon was operated for more than six months to treat reservoir water containing 15–38 μg/L of bromide in southern China. Preozonation enhanced the removal of chemical oxygen demand using potassium permanganate as the oxidant (CODMn) and ultraviolet light absorbance at 254 nm (UV254) using coagulation—sedimentation but did not improve total organic carbon (TOC—-removal effectively. However, preozonation markedly enhanced the removal oltrihalomethane formation potential (THMFP) by the conventional process, and THMFP removal by the combination of preozonation and conventional treatment was 57% using an ozone dose of 0.8 mg/L. Almost no bromate formed during preozonation. An ozone dose of 2.0 mg/L (0.5 mg/L and 1.5 mg/L for pre- and postozonation, respectively) was found to be the optimal dosage for the maximum removal of organics (65% of THMFP, 52% of TOC, 63% of CODMn, and 84% of UV254) while keeping bromate under 5 μg/L. A combination of conventional treatment with preozonation should be a suitable alternative if the primary goal is to remove THMFP. [ABSTRACT FROM AUTHOR]

There has been no information available on the removal of Cryptosporidium oocysts or oocyst-sized particles under the sand filtration conditions normally used for swimming pool water treatment. A pilot sand filtration plant has therefore been constructed at The University of Wales Swansea and operated under swimming pool conditions (25 m/h downflow, 30°C, 1.5 mg/L free chlorine, pH 7.3 to 7.5, alkalinity 120–150 mg/L as calcium carbonate). Removal of fluorescent polystyrene particles of a size range (1–7 μm) similar to the size of Cryptosporidium oocysts (about 5 μm) without added coagulant was less than 50%. Removal of the particles under the operating conditions above but with the addition of either of the coagulants polyaluminium chloride (PAC) or aluminium sulphate was capable of giving better than 99% removal of the particles. [ABSTRACT FROM AUTHOR]

In rural areas, where passive filtration of surface water is a viable option, aquatic systems can become contaminated by antimicrobials from wastewater treatment plants or diffuse pollution. This study examined slow sand filter biomass (schmutzdecke) sorption behavior and removal efficiencies in a pilot roughing and slow sand filter that was fed 0.2 mg/L of five compounds from four classes of antimicrobials. High-performance liquid chromatography/tandem mass spectrometry (HPLC MS/MS) was used to analyze aqueous antimicrobial concentrations. Schmutzdecke sorption coefficients were comparable to those previously found for soils but did not correlate well with estimates derived from octanol-water partition coefficients. Roughing filtration exhibited low removal efficiencies, but antimicrobials with high sorption coefficients can accumulate in roughing filter waste and schmutzdecke. At the end of a 14- day slow sand filtration period, tylosin was not detected in filter effluent and trimethoprim was >99% removed. Slow sand filtration, however, exhibited <25% removal of lincomycin and <4% removal of the sulfonamide class of antimicrobials. Multistage filtration is regarded as an ineffective treatment method for antimicrobials with low filter-media sorption coefficients. [ABSTRACT FROM AUTHOR]

The article discusses the new trends in mechanical and nonmechanical dewatering methods of residual wastes at water treatment plants (WTP). Traditional technologies and nonmechanical methods for free water removal rely on evaporation using dewatering lagoons and sand drying. It presents a research development that can alter environmental conditions and increase the evaporative process of nonmechanical dewatering beds and sand drying beds.

Surface irrigation water is a food safety risk due to susceptibility to contamination and varying turbidity that affects chlorination efficacy. Effectiveness of a combined high‐throughput, commercially available sand filter and UV‐C system to inactivate Escherichia coli (K12, and attenuated O157:H7) in simulated irrigation water of varying turbidity and actual irrigation water was investigated. Sand filtration reduced the water turbidity from ~600 nephelometric turbidity units (NTU) to ~200 NTU but did not effectively filter out E. coli (K12) [<1 log colony forming units (CFU)/ml]. UV‐C‐induced inactivation of E. coli (attenuated O157:H7) was modeled for various levels of turbidity (0–500 NTU), and the relationship between the D value for inactivation and turbidity was found to be linear (R2 >.97). Predicted UV treatment time to achieve 5 log reduction in water with turbidities of 100 and 300 NTU was 110 and 370 s, respectively. Validation performed with irrigation water (turbidity of 330 ± 82 NTU) showed that sand filtration reduced turbidity to 180 ± 57 NTU. Based on this, the duration of UV treatment required for 5 log reduction of E. coli O157:H7 was calculated (average of 237 s). Observed levels of inactivation, 4.7 ± 0.31 log CFU/ml, were not significantly different (p >.05) from the predicted level, 5 log CFU/ml, indicating a good model fit. [ABSTRACT FROM AUTHOR]

The plant also features a UV disinfection system (inset middle) for Cryptosporidium inactivation and a well water biological nitrate removal system (inset bottom). Additional features include a post-filtration ultraviolet (UV) disinfection system for I Cryptosporidium i inactivation and an innovative well water biological nitrate removal system. B Technology b : Helical upflow solids contact clarification (lime softening), recarbonation, gravity filtration, biological nitrate removal, UV disinfection. [Extracted from the article]

This article presents summaries related to water filtration. They include "Minneapolis Water Works' ultrafiltration plant gets off to a big start,"by Jonathan Pressdee, Shahin Rezania, and Chad Hill, "Riverbank filtration for IESWTR compliance," by William D. Gollnitz, Jennifer L. Clancy, Brock McEwen, and Stephen C. Garner, "Antimicrobial contaminant removal by multistage slow sand filtration," by Stephen J. Rooklidge, J. Ronald Miner, Tarek A. Kassim, and Peter O. Nelson and "A review of Cryptosporidium removal by granular media filtration," by Monica B. Emelko, Peter M. Huck, and Bradley M. Coffey.

A conference paper about the latest developments on membrane technology for the treatment of drinking water is presented. It states that water undergoes treatment processes including sand filtration, carbon filtration or ozonation, when water does not meet the stringent requirements of food legislation. It mentions that membrane technology can make water be mechanically purified and disinfected, and thus, could lead to the reduction of chemical additives such as chlorine or ozone in the water.